岩手県一関付近における上部新生界の花粉分析学的研究 (その3)
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概要
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The upper part of the Kazawa Formation and the lower and upper parts of the Mataki Formation, both of Upper Pliocene age, distributed in the southern part of Ichinoseki City and the northern part of Hanaizumi Town, are each composed of acyclothem. Each of the three cyclothems comprises from the lower to upper, conglomerate, sandstone, siltstone and tuff with lignite. Pollen analytical studies were made on the pollen from the lignite seams interbedded in the Kazawa Formation and the upper part of the Mataki Formation with the following results. The horizontal changes of the fossil pollen flora from the same stratigraphical horizon are closely related to the environment under which the lignite seams were deposited. The pollen grains of some members of the Taxodiaceae are dominant in the woody part of the lignite seams, but decrease towards the margin of the sedimentary basin and further outside. On the contrary, the pollen grains of Alnus show high value at the margin and outside of the basin referred to. From the fossil pollen flora is suggested that the vegetation, during the deposition of the Kazawa and Mataki formations, was nearly the same as represented in the woody part of the lignite seams. During the Late Pliocene, the vegetation of the northern part of Hanaizumi Town is thought to have been represented by the broad-leafed and coniferous forest, such as Fagus, Quercus, and some members of Taxodiaceae that grew in the temperate region. Intermingled in that vegetation are the trees of the warm-temperate region, such as Liquidambar and Nyssa. Therefore, compared with the present, the Late Pliocene forests of this area are inferred to have flourished under a mild and maritime climatic condition.
- 東北大学の論文
- 1972-03-10
著者
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